Grinding machine



. Noms, v193.1.

w. J. GUILD ET Al.

GRINDING MACHINE Filed May 31. 1929 7 Sheets-Sheet l Waldo -J GuLLcL l l HL NRT Nov. 3, 1931.

Filed Mlyv 51. 1929 W. J. GUILD ET AL GRINDING MACHINE '7 Sheets-Sheet 2 31a/ventola wQLCLO I. GLLLLCL redfP Bums NOV. 3,' 1931. lw 1 GU|LD ET AL 1,830,358

GRINDING MACHINE Filed May .51. 1929 7' sheets-sheet 3 l SWW/4450i (10c-.dde J. Guildv UgreclP. Burnsl Nov; 3, 1931. w. J. GUILD ET AL 1,830,358

GRINDING MACHINE Filed May 51, 1929 '7 Sheets-sheet' 4 fluo: u1

Nov. 3, 1931. w. J. GUILD ET AL 1,830,358

GRINDING MACHINE Filed May 31. 1929 7 Sheets-Sheet 5 ne a y l feas j -esq' l 138 199 196 v al l soa Isa :s+ 309 B00 1.6 l 7 Isa lss A 50 aaa l las so l w aos v aaa al aas m aa''s' l am F" 8 I a au l as aaa Ime/net Waldo J.- GuLLcL Hl recl P. Burns NOV, 3, 1931- w. J. GUILD ET AL 1,830,358

` GRINDING MACHINE 'Filed mayv 31. 192s 7 sheets-'sheet 7 ,6 I5 z 7 27a F l 5 I a f as 156 l s 266 27o 5 1a aa I4' 16o 69 1s 57 ass 264' 295 18 153 261 294' 1.93 .g4 a [s 3 E S/ 51 63 301 .I 150 16a 152 333 62 4%, so?

86 17.9l a o 'a I as] 2 l. -I, 17 as E'Ki/(Kfw B33 ;7,..,..-..-;I n//l/lllI/lf a r/.wfgqzy w/'r/l/l//lo G 177 r. \\\\;A.'\\\` a l 235 336 31o lll/II IM 7x1 I l Quiero U'. GLL'LLCL abtozmq Patented Nov. 3,y 19in UNITED STATES PATENT oFEicE WALDO J'. GUILD AN D ALFRED P. BURNS, 0F WORCESTER, MASSACHUSETTS, ASSIGNORS TO THE HEALD MACHINE COMPANY, OF WORCESTER, MASSACHUSETTS, A COR- machines.

PORATION OF MASSACHUSETTS GRINDING MACHINE Application filed` May 31, 1929. Serial No. 367,401.

The invention relatesto grinding machines, particularly to automatic internal grinding The invention involves certain improvements in machine organization and l arrangement. and combination of instrumentalities which can best be understood by reference to the disclosures ofcertain patents and patent applications on similar machines. Automatic precision grinding, particularly for internal Work, and to within very close limits, was made possible largely by the in'- ventionof J. G. McDonough, as disclosed in Reissue Letters Patent No. 16,141, dated August 11, 1925. According to the said McDono ugh invention, a gauge, preferably revolving at the saine speed as the workpiece, is maintained in position to enter that endiofthe workpiece bore which is opposite the end entered vby the grinding Wheel; when the grinding operation of said wheel enlarges the bore suiiciently for the gauge to enter therein, the machine, lin response to such entry movement, proc-ures withdrawal of the grinding wheel from said bore, to permit removal of the finished workpiece from the in achine.

The possibility of error 'in such precision grinding is further reduced, as described in Kempton and Gallimore Patent No. 1,7 31; 719, dated October 15, 1929, by causing the grinding wheel to be withdrawn from the workpiece just before the nal and finishing cuts are taken, and subjected to a dressing operation, in order that the said final and finishing cuts may be taken with a sha-rp cutting and perfectly cylindrical grinding wheel.

In the aforesaid Kempton and Gallimore patent, a gauge is vused to automatically inaugurate this intermediate dressing of the wheel. However, according to the invention of Guild Patent No. 1,682,672, dated October 28, 1928, this intermediate dressing operation inay be automatically. inaugurated by movement of the cross feed slide of the machine; thatA is, the position of the cross slide itself determines, in the grinding of each workpiece, when the dressing operation shall occur, suitable compensating means being provided to advance this position for successive grinding operations, in order to make each dressing operation effective on the grinding wheel.

' For increasing the rate of production of such automatic machines, the copending application' of Highberg, Serial N o. 99,287, filed `April 2, 1926, discloses an' automatic work loader adapted to take a fresh workpiece from' a magazine and place it in the chuck at the completion of every grinding operation.

lin such a machine, equipped with gauging or tothe present invention, cross slide operat ing means is depended upon to inaugurato' the dressing stroke to dress and true the grind-.

ing wheel, thereby dispensing with one of the separate gauges used in the Kempton and Grallimorel patent. The final runout of the grinding table, however, is made responsive to a rotating gauge of the McDonough type, since this is the most accurate known method of fixing the size of aworkpiece. It will thus be seen, that the machine retains to the fullest extent the advantages of the McDonough reissue patent principle, coupled with the advantages of an automatic dressing stroke, just prior to the coming to size of the workpiece in accordance with the patent of Kempton and Gallimore, together with the simplicity of operation of this function 'prior to the dressing operation, since the amount of material which is removed from the grinding wheel is thus made more nearly atent to Guild. The fore-- ioo a constant quantity. Another object of the invention, therefore, is to provide means for reducing the amount of cross feed between the grinding wheel and the work before the dressing operation takes place.

A work loading mechanism operating according to the principle of the aforesaid Highberg application is disclosed in the accompanying drawings, but not described in detail, because it does not differ in eunction or mode of operation from the work loader shown in said application. It is illustrated merely to make the machine complete and to give utility to various other mechanisms which are disclosed and described. The present invention provides automatic fluid pressure operated means to open and close the workholding chuck, comprising a cylinder mounted on the axis of rotation of the chuck and containing a rotating piston whose iston rod is the draw rod for the chuck. Thls constructional feature has greatly simplified the organization of the workhead. y

Another object of the present invention resides in the provision of fluid pressure operating mechanism to reposition the cross slide at the end of each grinding operation.

The invention further involves an imporl tant improvement in the McDonough system of calipering by a rotating gauge. ln the McDonough patent and other subsequent patents and applications, the gauge is moved against the workpiece at each reciprocation of the grinding wheel. This involves an unnecessary shock to the gauge and to the workpiece. A very important object of the present invention involves the provision of means to hold the gauge from engaging the Work-piece until a specified art of the grinding operation is complete This is made possible, in the illustrative embodlment 'of this phase of the invention, by using the position of the cross slide, that feeds the grinding wheel in relation to the workpiece, as an auxiliary gauging means to determine when the rotating gauge shall be allowed to come up to the workpiece.

Further objects of the invention include the synchronization of the various motions of the machine, and the organization of most of them into a complete Huid pressure operating system. It has been found most advantageous to perform periodic operations, of

. means. The coordination of the whole into a. complete system with the smallest possible number of actuating valves is an important object of the invention.

Further objects of the invention will be made apparent as the description proceeds.

Fig. 1 is a front elevation of a grinding machine incorporatingf our invention.

Fig. 2 is a rear elevation of the machine.

Fig. 3 is a side elevation of thefront por-.

tion of the workhead, showing the chuck in vertical axial section.

Fig. 4 is a plan View of the cross slide for the workhead.

Fig. 5 is a front elevation with the cover of the box removed, of the cross feeding mechanism for the cross slide of Fig. 4.

Fig. 6 is a sectional view on the line 6, 6 of Fig. 5.

Fig. 6a is a representation of a certain cam on an enlarged scale.

Fig. 7 is an isometric view of one of the cross feed stop magnets and automatic latch for the armature thereof.

Fig. 8 is a vertical axial sectional view through that part of the workhead just to the left of the portion shown in Fig. 3.

Fig. 9 is a sectional view on the of Fig. 8.

Fig. 10 is an end elevation of the gauge rod operating mechanism.

Figs. 11 and 12 are front and rear elevations respectively, of the switch mechanism that is actuated by the rotating gauge, the

line 9, 9

cover of the switch box being removed in Fig. 11.

Fig. 13 is a front elevation, with the cover partly broken away, of the cross slide operating mechanism for the wheelhead.

Fig. 14 is a vertical axial. sectional View, taken on the line 14, 14 of Fig. 13.

Fig. 15 is a diagrammatic representation of the piping of the machine, showing the various valves and cylinders, however, in correctaxial sectional representation.

Fig. 16 is a wiring diagram.

Fig. 17 is a view showing the dog-resetting member in relation to the sliding dog.

Like reference characters refer to like parts throughout the drawings.

Referring to the drawings, particularly to Fig. 1, the machine provides the usual reciprocatory table or carriage 1, which is ordinarily provided in any internal grinding machine. In such a machine, either the grinding wheel or the work to be ground may be carried on the table 1, the reciprocation of the latter being utilized in either case to produce a relative traversing movement between the grinding wheel and the work. As here shown, the table 1 supports and carries a wheel head 2 of the usual construction,- while the work which is to be operated upon is held in a workhead 3, the latter being carried by a bridge 4 which spans the slideways provided by the machine frame for the back and forth movement of the table l.

This back and forth movement of the table 1, to cause the grinding wheel 5, carried on the rotating spindle 6, to make the required interior traverse of the rotating workpiece, is imparted by fluid pressure controlling and reversing mechanism, which is not per se the subject of the present invention, but which is chine.

disclosed in Patent No. 1,582,468 to Heald and Guild granted April 27, 1926. However, a brief description of such mechanism is necessary to a clear understanding of the present invention, and such will now be given.

rLhe machine provides a cylinder 7 con- ,taining a double acting piston whose piston rod 8 is connected to the table 1 as shown in Fig. 1. The cylinder 7 is shown in Fig. 15. Referring to this ligure, fluid under pressure is admitted to one end or the other of cylinder 7 from any source of supply, such as a pump 10, which communicates through valve means that will be described, with a supply line 11, which leads to a reversing valve 12 disposed ina suitably apertured casing 13 that is located on the front of the ma- The position of the valve 12 .determines the flow o f pressure medium to one end or the other of cylinder 7, by way of pipe 14 or pipe 15, as the case may be. The return of pressure medium from the reversing valve 12 is by way of a pipe 16, which leads to a pump supply chamber or tank, not herein illustrated.

The casing 13 provides a passage 18 to the reversing valve 12, from the fluidpressure supply pipe 11.A The passage 18 is providedV with a rotatable plug or throttle valve 19,

adapted to be adjusted by a handle 20 (see Fig. 1) the position of which determines the quantity of pressure Huid flowing through the passage 18, and hence the speed at which the table'l is reciprocated. r

Pipes 14, 15 and 16 are connected to the reversing valve 12 by -means of passages 21, 22 and 23, respectively. The valve 12 is adapted to be oscillated, and is so formed that it will connect passages 18 and 21 at the same time as it connects passages 22 and 23, this being the position of the valve in Fig.

1. In the other position ofthe. valve 12, itf

' connects the passages 22 and18 together, also the Passages 21 and 23, Thus, as will be readily apparent, one position of the valve 12 subjects the left hand side of the piston in cylinder 7 to the fluid pressure generated by the pump 10, while at the same time connecting the right hand side of the pist/on to the exhaust pipe 16, and the other position of the valve 12 reverses these conditions.

Thus the direction in which the table 1 i moves is reversed every time the valve 12 is moved from one extreme position to the other extreme position, while it is apparent that if the valve is placed midway between its extreme positions, the piston will be urged neither to the left nor to the right. In order to control the oscillatory valve 12, itis fasten-ed to a shaft, not shown, to which is secured a hand lever 24, Fig. 1. The hand lever 24 is connected by'avpin and slot connection with a reversing lever 25 which is pivoted at 26 to the machine frame. The upper part of the member 25 is adapted to be engaged by spaced adjustable dogs 27 and 28 carried by the table 1.

Associated with the reversing lever 25 or the hand lever 24 is a suitable ldetent or snapover mechanism, not shown, which may be of any suitable type, such as that shown, for exam le, in the aforesaid patent to Heald and uild. It will thus be apparent, that if the prongs of the reversing member 25 are located so as-to be struck alternately by the dog 27 and the dog 28, the carriage l will be reciprocated through a definite stroke.

The present machine makes use of the table stroke controlling dogs and associated mechanism described in the aforesaid patent, Guild No. 1,682,672. The mechanismy disclosed in theaccompanying drawings for this purpose is the same as that shown in said Guild patent, with mere changes of form and shape, and hence will be very briefly described herein. As shown in Fig. 1, the left hand table dog 27 is carried by a block 29 which is slidably mounted on the table 1, but normally maintained in spaced relation to a fixed block 30 by means of a latch device 31. The block 30, the same as the block 32 that carries dog 28, is adjustably fastened to the table 1 by means of thumb screws 33, 33 engaging a suitable screw rack 34.

suitably mounted on the front of the machine, as in a box or'casing 35, are a pair-of electromagnets 36 and 37, the former only being visible in FiU. 1, because it completely hides the latter. tlectromagnet 36 is provided with an armature 38 which forms one arm of a three armed member pivoted at 39, whose upwardly extending arm 40 normally, during the working reciprocation of the grinding wheel 5 in the internal bore of a workpiece, lies adjacent the right hand end of the latch member 31. The electromagnet 37, which may be seen in Fig. 16, is provided with an armature 41, to which is similarly attached an upwardly extending arm 42.

Energization of the electromagnet 36, with consequent elevation of the lever arm 40, due to attraction of the armature 38, results in an amplification of the normal stroke of the table 1-, by reason of the fact that the left hand table dog 27, afterthe latch member 31 is raised, does not swing over the reversing lever 25, but on the contrary is moved by the latter relative to the table 1. The outward stroke of the table, and consequently of the grinding wheel 5,y continues until such time as the block 29 brings up against the firmly fastened block 30, whereupon the resistance afforded is sufficient to swing the reversing lever 25 to the opposite position, resulting in a reversal of the travel of the table. The sliding block 29 is automatically returned to its originalposition with respect to the iso Atable 1`a more extended stroke to the right.

This act-ion takes place by reason of the 'fact that the left hand table dog 27, instead of being firmly attached to its carrying blockas is the case with the right hand table dog 28, is pivotally mounted 011 its carrying block 29, normally resting by gravity 1n the position shown in Fig. l. The lever arm 42 is 1n the same vertical plane as the right .hand prong of the reversing member 25 with which the dog 27 contacts, and consequently, when said lever arm 42 is raised, the dog 27 on the next right hand stroke of the table rides on the inclined surface provided by the lever arm, clear of the reversing member 25, thus permitting the table l to continue 1ts movementto the right without being influenced by the normal reversing mechanism.

The table 1, under these conditions, continues to the right well beyond the range of the limited dressing stroke heretofore described, and until such time as a third revers` ing dog 45 engages one or the other prongs of the reversing lever 25. lThe dog 45 is formed on the end of a block 46 whichl provides a thumb screw nut 33 for adjustment along the table. v

From the foregoing it will be seen, that during the preliminary or rough grinding operation, the table 1 automatically traverses back. and forth over a limited although "adjustable range;y that thereafter the energization of the electromagnet 36 results in giving the table a limited stroke to the right, for the purpose of dressing Athe grindingwheel 5, as will more fully appear hereinafter; and that finally the energization of the magnet 37, results in giving the table a still further stroke to the right, during which time the ground workpiece is discharged from the machine, and an unground oney placed in' the',

work-holding chuckfrom a suitablemag'a zine 47, the change being effected by meansl of a chute'48 and a transferring device 49, the exact construction and mode of' operation of which will'not be herein described since such forms the subject matter ofl the copending application of Highberg above referred to. yThe foregoing machine motions, and many others which will be hereinafter described, are inaugurated by thetelectromagnetic instrumentalities illustrated in Fig; 16.

As already stated, the machine of the in- -vention is a completely automatic one, and

once it is properly set up for the grinding of`a given size and -style of workpiece, it will not stop until either the supply of workpieces has been exhausted, or the grinding wheel has been worn beyond a usable size. Assuming, therefore, that the machine has been provided witha fresh grinding wheel 5, the magazine 47 filled, all adjustmentsv made, and the hand lever 24 shifted to the left to cause the wheel to start inward toward the workpiece, by movement of the table 1 to the left under the inuence of the fluid pressure motor embodied in the piston and cylinder unit, the table so continues until the dog 27 lifts over the corresponding prong of the reversing lever 25, whereupon the table 1 and grinding-wheel 5 continue to reciprocate, the latter in contact with a workpiece in the chuck of the machine. During this time the machine may be said to be under the control of the automatic reciprocating mechanism, and the grinding continues uninterrupted and unchanged until' the first electric contact is made in response to movement of the cross slide of the machine. For a proper understanding of this mechanism, which next assumes control of the machine operation, it will be necessary to understand first the general construction of -the cross feeding instrumentalities which feed the Wheel and work together on a line transverse to the reciprocation of the table 1, and secondly the means for actuating this mechanism and these matters will now be described.

In internal grinding machines it has been common to ,cause this cross feed by movement of the. workhead or movement of the Igrinding wheel head, and generally irrespecderstood that the Vinvention is not limited thereto.

Referring now to Fig. 3, a portion of the workhead 3 is shown, involving a rotatable' spindle 50 suitably mounted in bearings 50a, Fig. 8, which is adapted to be connected to va pulley 51, as by means of a multiple disc vclutch 52 only the outside of which is shown,

since it is of common construction. A belt 53. drivencf/rom any suitable source of power rotates the spindle 50 continuously except when the clutch 52 is moved to disengaged position by a mechanism which will be hereinafter described.

The entire workhead 3 is pivotally mounted on a cross slide 54, as by means of a pivot post 55 and concentric pedestal 56- the former fitting in the pivot hole 57 provided by the workhead 3. In' this manner the workhead can be adjusted angularly in relation to theaxis of the wheel5, in order to provide for the grinding of tapered bores in workpieces if desired. I y

The cross slide 54 is mounted in V-ways 58, 58 for movement transversely of the machine.

Such movement is produced by the angu! lar movement 'of a lever 59, whiclris ivoted at 60 to the kbridge 4, and one end ofp which 63 and 64 are provided by the lever 59 where it contacts the lug 61 and the cam 62, respectively.

Thecam 62 provides a generally involute peripheral surface, and by its intermittent revolution procures the cross feed between the grinding wheel and theworkpiece, by movement of the slide 54. This inward feeding movement of the slide 54 is opposed by springs 54a (see Fig. 4) arranged between' said slide and the -bridge 4; said feeding movement procures the compression of said springs. The mechanism to rotate the c am 62 is contained in' a box-like structure 65 mounted on'the front of the machine, preferably onthe bridge 4, as shown in Fig. 1.

As shown in Fig. 6, the cam 62 is fastened to a shaft 66 that is suitably mounted in ball bearings 67, 67 provided by the casing 65.

A hand wheel 68a provides means for manually controlling the position of the cam. The cam is rotated by ratchet and pawl mechanisms, constituting a coarse .feed pawl, a fine feed pawl, and means for adjusting the stroke of each; this mechanism in its details being of the same general construction as shown in United States Letters Patent No. 1,673,078, granted June 12, 1928.

Describing this mechanism. very brieiiy, therefore, the ratchet wheel is shown at 68 and is fastened directly to the shaft 66. Pivotally mounted on the said shaft 66 are re; spectively a two and athree armed member 69 and 70, the former providing an aim 71 upon which at 72 is pivotally mounted a pawl 73 that is urged into engagement with the ratchet 68 by' means of a spring 74. The member 69 also provides a cam portion 75 vand a. stop arm 76.

The three armed member provides an arm 77 upon which is pivotally mounted at 78 a pawl 79 that is also urged into engagement with the ratchet 68 by means of a sprmg 80. The three armed member 70 further provides an arm 81 having a cam portion 82 and a stop arm 83.

Referringto the fluid pressure diagram of Fig. 15, it will be apparent that pipes 84 and 85 are shunted into the pipes 14 and 15, re-

spectively, which supply fluid to the' left hand and right hand ends of the cylinder 7. Consequently first the pipe 84 and subsequently the pipe 85 will receive iuid under pressure, which is conducted, respectively, to the left and right hand ends of a cylinder 86 mounted in or under the box 65. AvAs the table 1 reciprocates back and forth, a piston 87 in the cylinder 86will likewise reciprocate, and referring back again to Fig. 5, a lever 88 provides a downwardly extending arm extending into a slot 89 rovided by the piston 87. The upper end o the lever 88 provides a roller 90 which is therefore oscillated back and forth, and in its path of oscillation lie the cam portions 75 and 82.

It will thus be seen that the members 69 and 70 are oscillated on the pivot consisting of the cam shaft 66, the amplitude of oscillation of each of said members 69 and 70 being 'determined by the shape of the cam surfaces 7 5- and 82 and by eccentric stops 91 and 92 which engage stop screws 93 and 94, respectively, provided by the arms 76 and 83. Springs 95 are employed to urge theiarms 76 and 73 towards the eccentrics 91 and 92. By means of levers 96 and 97 mounted on the front of the box 65, the positions of the eccentrics 91 and 92 can be adjusted, and consequently the amount of motion given to the pawls 73 and 79 can be adjusted, this mechanism being substantially the same as the structure disclosed in the patent to Kempton and Gallimore above referred to. I

The pawl 79 is the coarse feed pawl ordinarily moves a considerable number of the ratchet teeth at a given stroke, depending upon the setting of the lever 97, and is actuated at both ends of the stroke of the table l. This is due tothe fact that the cam 4 portion 82 is so -shaped as to allow the oscilordinarily moves the ratchet through a distance of 1, 2, 3 or 4 teeth, and is moved only -at one end of the stroke of the table 1, viz.

the left hand end. This is due to thev fact that the cam portion 75 is so shaped that the oscillatino' roller 90 cannot pass beyond it at one en of its oscillation. Assoclated with the pawls 79 and 73 are electromagnets 100 and 101, respectively, adapted to successively remove the pawls from the ratchet wheel 68 thus to render ineffective their oscillations. The means for withdrawing the pawls by energization of the electromagnets are the armature members 102 and 103 which are pivotally mounted in the box 65, and provide tail pieces 104 and 105 engaging rollers 106 and107 provided by the pawls 79 and 73, substantial] as descrlbed in the aforesaid atent to from the ratchet, it is vheld in the withdrawn position by latch means disclosed in the afore- According to the present invention, the' cross feeding mechanism just described provides means for putting out'of action the empton and Gallimore. When rst K one and then the other pawlis Withdrawn` j further provides means for procuring the dressing of the grinding wheel 5, this being .inaugurated bythe energization of the electromagnet 36. To that end the ratchet wheel 68 has fastened thereto a cam 111 inthe path of which is an adjustable screw 112, provided by an arm 113 pivoted at 114 in the box or casing 65. The arm 113 provides a portion 115 extending at right angles to its main portion, providing a pair of contact p0ints-.116 and 117, only the rst of which is shownl in Fig. 5, since the second is hidden behind it. In the path of movement of the points 116 and 117, which are illustrated diagrammatically in Fig. 16, is a pair of insulated terminals 118 and 119, respectively, which are carried by levers 120 and 121, respectively, whose hub portions are mounted on a pivot ystud 122 provided in the box 65.` rIhe positions of these levers can be readily adjusted by means of eccentric adjustment devices 123 and 124 controlled from dials 125, 126 on the front of the box. e

Referring now to Fig. 16, electric current may be supplied to the machine by any suitale means such as a. generator 130. @ne

terminal of this .generator is grounded as at.

131, while the other terminal connects to a lead 132 having many branches as shown.

en, in consequence of the movement of the cam 111, contacts 117 and 119 come together, these contacts being adjusted tov come together before the contacts 116 and 118, an

electric circuit is completed, which energizesl the magnet `100 in the following manner The current flows from the generator 130 through the conductor 132, through a branch lead 133 to a switch bar 134. The switch bar 134 is one of a pair of such bars, so located as t'o be engaged by a movable bar 13.5, provided by an oscillatory switch member 136, which is oscillated in a manner fully described in the aforesaid patent to Guild. It will be noted that at this stage in the grinding operation, and untll after the automatic dressing, the swltch member 136 is in the position shown in Fig. 16, with the bar 135 engaging the stationary bar 134.

Movable bar 135 is connected toa lead or conductor 137 which leads to one terminal of the magnet 100. The other terminal of the magnet 100 is connected'by meansof a conductor 138 to the contact 119, and since this Contact 119 is at that time in engagement with the contactl17, which is grounded at 139, the.

clrcuit is completed, and the electromagnet 100 isenergized.' v j This causes the coarse feed pawl 79 to be withdrawn from the ratchet wheel 68, and consequently the grinding proceeds with a fine crossv` feed, thereby procuring a gradual reduction in the spring or deiection of the wheel spindle 6.

1,sso,sas

Further feeding of the ratchet wheel 68, under the continued actuation of the ne feed pawl 73, moves the cam 111 and causes further lifting of the Contact arm 113.- This, after a definite number of reciprocations of the grinding wheel 5, causes the contacts 116 and 118 to come together, and thus energizes electromagnet 36 in the following manner Conductor 132,'whichhas already been described leads from one terminal of the generator 130, connects to a branch lead 140 which connects to one terminal of the electromagnet 36. The other terminal ofthe electromagnet 36 connects by means of a lead 141 to a stationary contact bar 142, which is at that timee'ngaged by a movable contact bar 143 carried bythe oscillatory member 136. The contact bar or plate 143 connects by means ofa conductor 144 with theI terminal 118, and thus without further description, it will be apparent that the electromagnet 36 is energized at this juncture. y

It has already been described how energiza tion of the electromagnet 36. resulting in the .raising of the lever arm 40, procures the withdrawal of the grinding wheelf5 from the workpiece. Simultaneously with this action a dressing device or diamond 145 is lowered into the path of travel of the wheel 5, thus dressing and truing it by predeterJ mined amount. The diamond 145 is mounted in asuitable plug or nib which is carried by an oscillatory member 146 that is mounted on the machine frame in a manner fully set forth in a patent to Guild and Grimshaw No. 1,655,903, granted Jan.10,'1928; It is un-A necessary, therefore. to describe the details of the mounting of the diamond in this present specification, except to'note that said diamond is lowered bv the rearward movement of a lever 147 which draws rearwardly a link 148. said lever being fastened lto a shaft 149 and operated in a manner which willnow' bedescribed.O l 1 f v Referring to"Fig. 15, -a branch ypipe 150 shunted into the Huid supply pipe 11 leads Huid to an entrance port 151 of al valve generally designated by the numeral k152. In

the normal position of the valve-member 153 in thi@ valve, the port 151 is kept covered. Referringto Fig. lfttached to the armature 38 and arm 40 is a third arm 154which is connected to thevalve 153; so that when.' j

operating and adjusting mechanism is mounted, which -is indicated at 158 in Fig. 1. In the cylinder 156 is a piston159, which, when the fluid is admitted thereto, is driven rearwardly of the machine. A 1ugl60'on the end,V l

1,sao,sss

of the piston 159 is in engagement with a portion of. the lever 147, and consequently rocks it rearwardly.

When, as already described, the grinding wheel is returned into the workpiece subsequentto the dressingoperation, the diamond 145, by movement of the table 1, is returned into its original position as shown in Fig. 2. This is effected mechanically by means of a cam bar 162 adjustably mounted on the rear of the machine, as shown in Fig.

- 2, said cam bar striking a roller, not shown, that 1s provided by a forwardly extending arm of the bell'crank lever 147. This action, of course, drives the piston 159 into the cylinder 156 again, and consequently forces the fluid out of said cylinder. The valve 153 has, yby this time, been returned to the position shown in Fig'. 15, and consequently' the Huid is exhausted through a port 163 which communicates with a supply tank, or other source of fiuid pressure. The manner in which the valve 153 is returned to its initial position is described somewhat more at length in the patent Vto GuildNo. 1,682,672 above referred to; suffice it to say herein that said return is effected by engagement f a cam surface 164 provided bythe sliding block 29 with a latch portion 165 on the lever 40.

The roc-king of the shaft 149 in order to place the dressing device 145 in dressing position, andsubsequently remove it from the path of the grinding wheel 5 is made use of,

lirst to slow down the reciprocatory traverse of the table 1, so that the dressing of the wheel 5 will take place at a slow linear speed in orderthat no high spots maybe left in the wheel, and second to cause the reciprocatory traverse of the table 1 during the final ano finishing cuts, subsequent to the dressing op eration, to be taken at any predetermined -speed of traverse intermediate the dressing speed and the preliminary or roughing speed,

inclusive of both of them. To that end', an arm 166, only the hub of which is shown in Fig. 2,'is .suitably fastened to the shaft149, and to the inner end of the arm 166 is attached alink rod 167. The rocking motion of the shaft 149 to lower the diamond 145'consequently involves a raising of the link-167. At the lower end of the rod 167 are a pair of adjustable nuts 168 and 169 in between which is located one arm 170 of a bell crank lever 171. AThe upper end of the latter is connected to the outer end of a valve member 172, which is shown in section in Fig. 15. The valve member 172 is -contained in a casing 173 and provides an entrance port 174 connected by means of pipe 175 with thepump 10. The entrance port 174 is in communication with a hole 176 through a sleeve 177 by means of I which the fluid'is at all times admitted to through a gap left between the sleeve 177 and another sleeve 181, with the fluid pressure pipe 11, which admits fluid to the main reversing valve that controls the reciprocation of the table 1. When, therefore, the valve member 17 2 is moved to the right, Fig. 15, as already described, the cylindrical portion 178 thereof covers part at least of a circular orifice extending between sleeves 17 7 and 18,1, and which is in effect a port 182, and thus acts as anfindependent throttle to automatically lower the speed of travel of the table 1 for the dressing operation.

The movement of the valve member 172 to the right has a further important function in allowing the gauge of the machine to gauge the work from that time to the finish of the grinding operation, but before describing this, the construction and general operation of the parts in the workhead will be set forth.

Referring to Figs. 3 and 8, the chuck spindle 50 is hollow, and inside of which is a tubular draw rod 183 the longitudinal movement of which causes the chuck 184 to grip or release a workpiece. The ydraw rod 183 revolves by reason of the fact that it i's frictionally connected to a spider 185 which in turn is attached as byA screws 186 to the body 187 of the chuck, the latter being revolved by reason of the fact that it is directly attached to the rotating chuck spindle 50.

lVthin' the draw rod 183 is a third hollow rod, viz. the gauge rod 190. This rod is also revolved, by reason of'a spline 'connection 191 with the draw rod 183. It will thus be seen that the three rodsor tubes 50, 183, and 190,

revolve simultaneously about a common axis, Y

the (first being held from longitudinal movement in bearings 50a, but the last two bemg independently longitudinallyl movable inside of said tube 50.

The gauge rod 190 provides a screw threaded portion 192 and a plain portion 193, both of which extend rearwardly beyond the draw rod .183. A tubular member 194 is in screw threaded engagementwith the threads 192 and firmly attached thereto by means of a check-nut 195. This tubular member 194 provides a stuffing box 196 which forms a water-tight' connection between the said tubular member and the gauge rod.

The tubular member 194 provides a shoulder 197 and screw'threads 198 on which is a nut 199. 4By means of the nut and the shoulder, the inner race 200 of a ball bearing 201 is firmly fastened to this tubular member 194. It will be seen that the tubular member revolves with the gauge rod 190. A non-rotatable pipe `202 provides a portion 203 eX- tending into the tubular'inember 194, and `having av flange 204 in a stuiiing box 205 provided therein. The non-rotatable pipe is held in place by means of al sleeve 206 and a flanged nut 207, which compress the stufhng box onto the flange 204. This pipe 202 has a flexible connection 202a with the usual water pump, not shown, provided by or associated with all grinding machines of this class, by means of which water or other suitable coolant is admitted into rthe sleeve 194 and thus into the rotating gauge rod A190, through which it is carried direct-1y to the workpiece in the chuck. The rod 190 thus serves as a coollant conveying pipe as well as a gauge roc.

Still referring to Fig. 8, the workhead 3 provides, on the under part thereof which over-hangs the left hand end of the machine, a double pair of alined bearing portions 208, 208. These bearing portions 208 slidably receive two rods 209. Referring now to Fig.l 10, the rods 209 are suitably fastened as by means of nuts 210 to a plate 211 which provides a semi-circular yoke 212 supporting -the outer race of the ball bearing 201. The

plate 211 further supports a member 213, suitably fastened to it as by screws 214, which provides an upwardly extending split portion-215 that surrounds the pipe 202 and may be suitably clamped on said pipe as by means of a screw 216. Thus it will be seen that rearward movement of the rods 209 and consequently the plate 211 will result in rearward movement of the gauge rod 190.

'By means of a spring 217, which is attached to a stationary post 218 at one end and to a pin 219 adjustably fastened by means of a nut 220 -to the plate 211 at the other end, these parts are urged to the right, Fig. 8, to carry the gauge 221 into engagement with the bore in the workpiece a. The parts are shown in this gauging position in Fig. 8. Of coursethe gauge 221 can not enter the workpiece until the workpiece is ground to the correct size, and inasmuch as the grinding wheel 5, in its traversing movement to grind the workpiece, must pass completely through the latter, the gauge must be out of the way of the grinding wheel on the extreme left hand stroke of the latter.- Consequently means is provided to shift the gauge rod forcibly to the left at every reciprocation of the table.

As shown in Figs. 8 and 9, a triangular bracket 222 is mounted on the rods 209 and `suitably fastened thereto. This bracket adjustably supports a bolt 223 which is secured in any suitable position by adjustment of a nut 224. The end of this bolt is in the path of travel of the table 1, and consequently the movement of the table periodically shifts the whole mechanism to the left. l

The periodic shiftingr of the gauge rod and lgauge by movement of the grinding machine table or carriage is not the subject matter of the present invention, being shown in a patent to Conradson, et al., No. 1,534.302. According to said Conradson, et al. patent and also the aforesaid McDonough reissue patally wears them down, and necessitates their y frequent inspection (a great number yof different size gauges being, of course, carried in stock) to see that they are of the correct size. The present invention, therefore, provides a distinct improvement over the prior patented constructions, in providing means for holding the gauge rod 190 and gauge 221 and associated parts to the left until such time as' the preliminary grinding of each workpiece is completed. v In other words, the machine of the present invention provides automatic workpiece measuring. means of one type, to determine when the automatic workpiece measuring means of the reciprocating and rotating gauge type shall come into operation, thus relieving the latter from the onerous and unnecessary part of the work, and bringing it into operation only to secure that final degree of accuracy which is beyond the capabilities of the other measuring means. This mechanism will now be described.

Still referring to Fig. 8, a cylinder 225 is suitably formed in the workhead 3 or a casting 226 attached to it. In this cylinder 225l is a piston 227 having a piston rod 228. Therod 228 ext-ends through an end wall 229 that forms the boundary of the cylinder 225, and is in abutting engagement with the right hand portion of the plate 211.

Opening into the right hand side of the cylinder 225 is a port 230 and normally, during the preliminary grinding operation and before the dressing contacts 11-6 and 118 are brought together, fluid under pressure is admitted to the cylinder 225 through the port 230, and thus the piston rod 228 is held to the left to its fullest extent, thus holding the gauge 221 and all associated parts to the left where it is impossible for the gauge to touch the workpiece.

Referring back, therefore, to Fig. 15, in which the piston and cylinder parts are shown in somewhat diagrammatic form, it will be seen that the port 230 is in communication by means of a pipe 231 with a port 232 through'the sleeve 177, which communicates with the interior portion of the valve 172 between the enlarged portion 179 and enlarged portion 233 at the right hand end of the valve member. This interior portion 234 of the valve is in communication through a port 235 with the entrance port 174 for the fluid, and thus in the normal position of the valve 172, the Huid is active against the end of the cylinder 227 as aforesaid. When, however, the valve member 172 is moved to the right, which takes place in response to energization of magnet 36, the

enlarged portion 179 of said' valve member covers'l the port' 235, while the enlarged portion '233 uncovers a port 236 leading back to the pump supply chamber. This immediately relieves the pressure on the piston 227 and the latter, owing to the influence of spring 217, is forced into the cylinder, and the gauge 221 and all associated parts are free to move to the right, obstructed only by the vperiodic movement of the table 1 and the workpiece itself. l

In the description of the machine as a whole, it will now be seen that the grinding has proceeded to a point where the rough grinding has been inished, and the cross` feed slowed down to apoint where the side pressure on the spindle 6 has been relieved. The stroke of the table 1 was then extended, and the wheel 5 subjected to a dressing operation by passing it twice in front of a diamond 145 and in engagement therewith. This operation, as will be remembered, took place at a slower speed of movement of the table 1 than the normal movement, owing to the movement of the valve 172 by means of the link 167 operated from the oscillating shaft 149. At least, since the valve 178 and 19 are in series, it can be said that the dress` ing operation will take place at a low speed whatever the adjustment of the valve 19.

The sliding block 29, is then restored to its original position on table'l as already set forth and the wheel 5 returns to the workpiece. This is accompanied by a return oscillation of the'shaft 149 and the return of the dressing point 145 to' the position shown in Fig. 2. Thisreturn oscillation of the shaft 149 does not completely reset the valve 172, since there is alostmotion between the nuts 168, 169, on the rod 167 and the portion 170 of the bell crank lever 171 that is located between them. Thus the enlarged portion 17 9, while it moves somewhat to the left in response to the return of the grinding wheel 5 into the workpiece, does not uncover the port 2 35 again during the grinding of this particular workpiece, or at least the nuts 168, 169 can be set' so that it will not, and they are intended to'be so set, in order that the gauge I221 may from this time forth take control of the machine and bring the grinding opera-- tion to a termination when the workpiece has been ground to the correct size.

It has just been stated that the machine is now under the control of the gauge 221. As the machine was previously'under the control of the cross slide operating mechanism and electric contacts operated thereby, it will .be apparent that provision must be made to transfer this control. To that end, the carrying block 3() provides a pair of downwardly hanging arms 238 and 239 which are pivotally mounted on said block and capablev of being lifted from the position shown in Fig. although not capable of being depressed from said position. In the path of the arm 238 is an upwardly extendin arm 240 of the switch member 136, while 1n the path of the depending arm 239 is an arm 241 of said 'switch member. The-location of the oscillatory switch member -136 on the mamains until the commencement of a subsequent grinding operation. Thus it will be seen, that by the dressing stroke aforesaid, the circuitsthrough magnets -36 and 100 are definitely broken, thus preventing any further dressing operation despite the maintenance of engagement between the contacts 116 and 118, and 117 and 119, respectively. The pawl 79 is not, however, allowed to contact the ratchet wheel 68 again, owing to the beforementioned latching mechanism'of Kempton and Gallimore Patent No. 1,673,-

Referring now to Figs. 10 and 12, a boss 242 is provided by the plate 211, and a rod 243 extends through this boss 242, being suitably fastened thereto in any ad]usted position, as by means of a screw threaded portion 244 which engages threads inside the boss, and is locked in-position by means of a check nut 245, b'oth the check nut and the head of the rod having knurled thumb portions as shown.

Referring now to Figs. 1, 11 and 12, it will be seen that a box or casing 246 is suitable attached to the Workhead as to the casting 226 provided thereby. The rod 243 extends into this casing but normally is not in engage- -ment with a tail piece 247 provided by a latch member 248. The latch member 248 is urged downwardly by means of a spring 249, and during the grindingoperaton holds a contact member 250, which carries a contact point 251, in open circuit position. The parts are shown in this position in Fig. 16. The contact member 250 is secured to a shaft 252 which is suitably journalled in the box 246, and therefore, the contact member 250 may be said to be pivotally mounted in the box;

v then the gauge rod 190, sleeve 194, pipe 202,

bracket 215, plate 211,rods 209 and all associated parts are moved to the right. Since the rod 243 is attached to the plate 211 said rod is moved to the right, Fig. 11, and`the end of the rod engages a tail piece 247 of the latch 248, thus lifting the latch from the tail piece of the contact member 250, allowing the terminal 251 to engage the terminal 254 under the influence of the spring 253.

This completes an electric circuit as fol- 20 1 ows Referring now to Fig. 16, a branch lead 255 from the main conductor 132 carries current to one terminal of the electromagnet 37. The other terminal of the electromagnet 37 is connected by means of a conductor 256 to the stationary contact terminal 254.' Since the movable contact terminal 2'51 is grounded through the lever 250, as shown at 257, the circuit is completed and magnet 37 is energized. This causes the lever arm 42 to be raised into the path of the table-dog 27., and procures an extended movement of the table 1 to the right resulting in carrying the grinding wheel 5 out of the workpiece.

The bringing ntogether of contacts 251 and 254 results also in withdrawal of the fine feed pawl 73 from the ratchet wheel 68. As shown in Fig. 16, another branch lead 258 from the main conductor 132 carries current to the electromagnet 101, the other terminal of the electromagnet being connected by a conductor 259 to the terminal 254. It will thus be seen that the magnet 101 is energized coincidently with the magnet 37,and the fine feed pawl 7 3 is withdrawn from the ratchet wheel 6,8, and held in such a position by the latch means already mentioned. Thus at this time both pawls 79 and 73 are held awa-y from the ratchet 68, which is consequently free to be turned in a retrograde direction in order to prepare. the machine for the grinding of a fresh workpiece. This retrograde motion of the ratchet 68, involving the turning back of the cam 62 to reposition the cross slide 54, takes place in the following manner As shown in Fig. 16, a third arm 260 is associated with the arms 41 and 42 of the three armed member pivotally mounted onthe stud 39 and associated with the rear electromagnet 37. The lower end of the arm 260 is connected to a valve member 261 which is located in the valve casing 262 that may be and preferably is an exact duplicate of the valve 152. When the valve member 261' is moved to the right by reason of the energization of the magnet 37, fluid is allowed to enter through a port 263 and ultimately conducted by a port 264, pipe 265 and a port 266 to a cylinder 267 in which is a piston 268. The cylinder 267, as shown in Fig. 5, is located in the casing 65 on the front of the machine, and is connected at 269 to a lever 270 that is pivotally mounted at 271 and provides a segment rack 272 at its upper end. The segment rack 27 2, as shown in Figs. 5 and 6, is in engagement with a gear 273 fastened to the cam shaft 66, and consequently movement to the' right of the segment 272 results in a counterclockwise movement of the cam 62 to bringthe portion of its involute surface of small radius into contact with the shoe 64 on the lever 69.` This permits the springs 54a. to reposition the cross slide 54, so as to allow the grinding wheel 5 to enter afresh workpiece which will be placed in the 'chuck by the loading device 49.

The outward movement of the table 1 causes the transferring device 49 to remove the ground workpiece from' the chuck, and to place a new workpiece, taken from the maga- Zine 48, into said chuck. The movement of the transfer mechanism 49 and the .-manner in which it operates, will not be described herein in detail, since it forms no part of the present invention and i is described and claimed in the aforesaid copending application of Highberg above referred to. A brief mention of, this function, however, serves to point utility to the following further fuuctions which the outer movement of the table 1 produces. Said movement of separation causes, first thestoppage of the chuck spindle 50, and immediately thereafter the movementofthe draw rod 183 to the right, thereby opening the chuck for the discharge of a 'ground workpiece and subsequent disposal therein of an unground workpiece.

To that end a cam 274, adjustably mounted on the rear of the table 1, provides a pair of surfaces 275 and 276 which are adapted, by movement of the table, to be successively brought into engagement with a roller 277 provided by a bell crank lever 278. The bell crank lever 278 is pivotally mounted at 279, and normally urged in clockwise direction by a strong coil spring 280. The lower end of the bell crank lever 278 is connected to a sliding valve member 281. located in a valve 282, the internal construction of which is illustrated in Fig. 15.

As shown in Fig. 15, the valve member 281 provides two reduced portions 283 and 284 bounded Vby portions of full diameter 285. 286 and 287. Normally, before the table runs out llld llc:

lili

as heretofore described, the reduced portion 1a?.

always in communication with it, while the 13p latterconnects by way of a pipe 292 with a. port 293 provided on the forward or right side of a piston 294, located in a cylinder 295 that surrounds the draw bar 183. (It should be observed that the cylinder 295 1s seen in Fig. 8 -as from the front of the machine, and in Fig. as from the back. We shall hereinafter treat this cylinder as thoughV it were viewed from the front.)

Before describing the action of the piston and cylinder unit 294, 295, the other fluid connections of the valve 282 will be set forth.'

-Prior to the movement of withdrawahof the table 1, the valve member 281, besides maintaining the ports 288 and 289 in direct connection, maintains a pair of ports 296 and 297 in connection with an exhaust port 298, this connection being established by the reduced portion 284. The port 296 communicatesby way of a pipe 299 with a cylinder 300, having a piston 301 whose movementv actuates the clutch for the work spindle. The port 297 communicates by way of a pipe 302 with a port 303vopening on the right hand side of the piston 294. Prior to movement of thebell vcrank 278 by the cam bar 274, therefore. the cylinder 300 is opened to the exhaust while the pressure of the fluid is maintained on the left hand end of the piston .f 294. Thus the piston 301 inthe cylinder 300 is in its lowermost position, and the clutch 52 is in its engaged position. Also the piston 294 is in its right hand position which causes the clutch fingers to firmly grip aworkpiece.

At this' point the novelty of the present construction of fluid pressure means for operating` the chuck should be noted. The piston 294 is fastened, by means of a screw 304 direct-ly to the chuck draw bar 183 which, as it will be remembered, rotates with rotation of the chuck spindle 50. Thus the piston 294 rotates within the cylinder 295. and consequently no mechanical connections to transfer rectilinear movement to a rotating partare needed in the present machine, since the piston 294 is moved'by the pressure of the fluid. The piston 294 rotates without excessive friction in cylinder 295 by reason of the fact that the fluid used to produce the pressure is oil-which, of course, is a lubricant.

that the cam lsurface. 275 has engaged the roller 277 by reason of the movement of the table 1, thus moving the bell crank 278 (Fig. 2)y the motion imparted to the valve 285 will be just sufficient to carry the portion 286 to the right of the port 296. This will admit the fluid from the entrance port- 288 to the l port 296, and will result in the raising of the piston 301 in the cylinder 300. The piston 301 is shown in Fig. 2, and in engagement with its upper surfa ce is a roller 305 provided by a lever 306. The lever '306 is keyed to a shaft 307 which is shown in Fig. 2 and also in Fig. 3, and to this shaft 307 is'keyed a yoke member. Referring agam to Flg. 15, and assuming chine for a new 308 which controls the disc clutch 52. Upward movement of the piston 301, therefore, results in disconnecting the clutch 52, and the chuck spindle 50, and all associated parts come to a stop. 'A

Further'rearward movement of the table 1 brings it to the position shown in Fig. 2 in which the cam surface 276 is in egnavement with the roller 277. This results in Zfurther movement of the valve member 285 to the right, carrying the portion 286 thereof just beyond the port 297, but not so far as to cover the port 298. In this position of the parts,

the valve port 297, as well as the port 296, is connected to the eut-rance port 288 and this admits fluid to the pipe 302 and to the r1ght hand end of the cylinder 295. This forcesV the piston 294 to the right eFig. 8) which pushes the rod 183 with it, and thus opens the chuck fingers for the discharge of the ground workpiece and the reception of a new one. fluid exhausting from the right hand end of the cylinder 295 in the following manner The pipe 292, it will be remembered. having -a port 289 in the valve 282 leads to the right hand end of the cylinder 295 (or the left as viewed in Fig. 15). TVith the valve in the furthest extreme right hand position described, an annular-chamber 309, which communicat-es through holes 310 with an axial passage 311 provided in the valve member 281, is over theport 289, and thus the fluid can exhaust to the interior passage 311. The passage 311 is in communication at that time by way of holes 312 with the right hand recessed portion 284 which covers the exhaust port 298.

Movement to the right of the valve member 285 just described, which admits fluid to the pipe 299, necessarily also results in the admission of fluid under pressure into a pipe 313 that is shunted into said pipe 299. The pipe 313 communicates with an entrance port 314 of a chamber 315 provided on the left hand end of the valve casing 173. The left hand end of the chamber 315 is bounded by a cylindrical portion 316 of the valve member 172 which has a. substantially larger area than the cylindrical pbrtion 178 of said valve Entrance of the fluid into this chamber, therefore, shifts the whole valve member 172 to the leftnto its original position as shown in Fig. 15, preparing the magrinding operation at the highest adjusted speed of table travel, as determined by the setting of the throttle valve 19.

The outward travel of the table 1 procures also the release of the pawls 7 3 and 7 9 from the laching mechanism described in the aforesaid patent to Kempton andGallimore No. 1,673,078.

Referring now to Figs. 1, 5 and 15, a cam bar 317 is carried by the table 1, preferably by the sliding block 29. This cam bar, when the table runs out beyond the dressing position,` is adapted to engage a roller 318 on the end of an arm 319 pivoted to the machine frame at 320. Referring now to Fig. 16, a contact member 321 is carried by the arm 319, and adapted upon depression of said arm to engage a stationary contact 322. The latter is grounded as shown at. 323, and since the contact is connected by a conductor 324 to one terminal of a solenoid 109, and since the other terminal of said solenoid is reached by the conductor 132, the solenoid, at this stage in the operation of the machine, is energized.

The solenoid 109 has inside thereof a core 326, which is mounted on the rod 110 that connects the. separate latch means of the aforesaid invention. Energization of the solenoid 109 causes the core 326. and consequently the rod 110, to be moved to the left, and this pulls a pair of arms 327 and 328 to the left, thus rocking a pair of shafts 329 and 330, and withdrawing the'latches 331 and 332 from the tail pieces of armatures 102 and 103, and thus removing the guards 104 and 105 from the pins 106 and 107 and allowing the pawls 73 and 79 to reeng'age the ratchet 68. under the infiuence of springs 74 and 80.

The motion of the table 1 is ultimately reversed by means of the reversing dog 45, which as previously described engages the reversing member This dog 45. before it contact-s with the reversing member, engages the upper inclined surface of the lever 42. and thus rocks the three armed member comprising said lever 42, the armature 41, and the arm 260 in a clockwise direction to its original position, resetting the valve member 261 and opening the port 266 of the cylinder 267 through pipe 265 to an exhaust port provided in the valve 262. Thereupon the ratchet 68 is free to be moved by the pawls in the grinding of the next workpiece.

Substantially coincidentl with this revers- .1- ing action, the grinding wheel 5 is moved transversely of the machine, in order to compensate for the previous dressing of said wheel and to provide a-surface to contact the dressing diamond 145 during the grinding of the next workpiece. To that end the wheelhead 2. as shown in Fig.\2, is mounted on a cross slide 334 which is, in turn mounted on ways provided by the table 1.

Referring to Figs. 13 and 14. the position of the cross slide 334 is adjustable by means y of a screw shaft 336 upon the front. end of which is mounted a hand wheel In this manner the machine may be adjusted vto grind different sized workpieces. Outward move` ment of the table 1 procures a slight angular turning of this screw shaft 336, to compensate for the reduction of the wheel 5 by wear and dressing' in the following manner As shown in the aforesaid figures, a ratchet wheel 338 is fastened to the shaft 336, and

this ratchet wheel is adapted to be moved by a pawl 339 pivotally-mounted at 340 on an arm 341. The arm 341 is journaled at 342 to a sleeve 343 surrounding the shaft 336, and is normally held in its lowermost position by means of a spring 344. Vhen the table moves to the extreme right hand position, a` cam 345 attached to a rod 346 on the front of the machine engages a roller 347 mounted on the arm 341, and rocks the said arm upwardly. This forces the pawl 339 into engagement with a wedge member 348 which causes the pawl to engage the ratchet wheel and move it. The number of teeth through which the pawl moves the ratchet wheel is adjustable by means of an adjusting device 349 engaging one end of a bell crank lever 350 pivotally mounted at 351, and to which said member 348 is fastened, a spring 352 holding the bell crank lever in its position of adjustment.

It will be apparent that any other suitable mechanism for advancing the position of the cross slide 334 at the end of each grinding operation would suffice so far as the present invention is concerned. In order that the operator may have a guide as to when to stop the automatic operation of the machine by reason of the reduction of the Wheel 5 bevond eliicient grinding diameter, a pointer 353 and a scale 354 are provided.

The return motion of the table 1, to carry the grinding wheel /back again into the workpiece is accomplished by the removal of ythe cam bar 274 from the roller 277 on the end of the bell crank lever 278. The spring 280 then moves said lever in a clockwise direction, and this causes the valve 1n mber 285 to be drawn to the left to the position shown in Fig. 15. Without further description, it will be apparent that this action causes the fluid pressure to be made active again on the left hand side of the piston 294, thus causing the chuck jaws to grip the fresh workpiece presented to it by the loading device 49, and likewise opening the cylinder 300 to the exhaust port 298, thus causing the springs, not shown, in the clutch 52 to move it to engaged position. The new workpiecev is now in the chuck and is rotated therein and is ready for the entrance of the grinding wheel 5.

The resetting of the valve member 17 2, by reason of the entrance of the fluid into the chamber 315 as already described opens again theport 235 and admits the fluid under pressure to the cylinder 225, thus forcing the piston 227 to the left. This draws the gauge rod 190 and the gauge 221 away from the workpiece, allowing the grinding wheel to enter without interference by the gauge, and preventing the gauge from hammering the workpiece during the preliminary grinding. This action also, since it results in Inovement of the plate 211 to the rightjFig'12,

hold said member 250fin-open circuit posi' -tion until such time. at the end of the grinding of this next workpiece. as the gauge 221 enters the bore thereof.

A brief resum of the cycle of operation of the machine will now be given for a clearer understanding ofthe invention. Assuming the machine to be in the position shown in Fig. 1, the magazine et? loaded, and all ad` justments made, with the hand lever 24 and the reversing lever 25 in middle or neutral position, the operator starts the machine in operation by shifting the hand lever 24 to the left, thus swinging the reversing lever 25 to the right and causing the table 1 to move to the left under the inuence of the fluid under pressure which is admitted at that time to the right hand side of the cylinder 7 through the pipe 15. This movement of the table to the left causes the transferring device 49 to move rapidly toward the chuck, passing through a pair of jaws 359 which resilientl)Y hold a single workpiece. and lacing said workpiece between the chuck jaws. The moment the workpiece is in position between the chuck jaws. the roller 277 carried by the arm 278 drops from the cam sur-` face 276 to the cam surface275, and this results in aslight'left-ward movementof .the valve member 285. which is sufiicient, however. to cause the large portion 286.-.of the valve 287 to move to the left of port 297. thus connecting` said port to the exhaust port 298. This connects the left hand side (Fig. 8) of the piston 291 to the exhaust, through pipe 302. The same movement moves the enlarged portion 285 of this valve member just to the left of port 289. and consequently connects port 289 with the supply port 288. This results in admitting` fluid to the 'pipe 292, and thus to the rightl hand side of the piston 294 in the cylinder 295.

Since the piston 294 is at this time in its right hand position when viewed from the front of the machne, in which it holds the draw rod 183 to the right thus holdingthe cuckjaws 360 open` the resulting left hand movement of the piston 291 moves the draw rod 183 to the left andcloses the jaws 360 on the workpiece.

The moment the jaws have closed. the transferring device 49 moves away from the workpiece and -out ofthe -wajv of the oncomingr grinding wheel 5. this movement being effected in a manner which is no part of the present invention.

Further movement of the table 1 to'the left. as it is viewed on the front of the machine. carries the roller 277 along the cam portion 2:5. and finally oti' the end of said cam port1on. This results 1n giving the valve member 285 a further movement to the left, Figs. 2 and 15, which both illustrate this valve as viewed from the rear of the machine. This movement disconnects the port 296 from the fluid pressure port 288, and reconnects it to the exhaust port 298, thus allowing the fluid to exhaust from the 'cylinder 300, and .allowing the piston 301 to move down under the influence of the springs, not shown, in the clutch 52. Thus the chuck and all associated parts are rotated. to rotate the workpiece for the grinding operation thereon.

The grinding wheel 5 now enters the workpiece, the pivotally mounted dog 27 lifting over one prong of the reversing member 259 Just before the grinding wheel 5 enters the workpiece, the left hand arm 239 strikes the arm 2-11 of the switch member 136, and places said switch in the position shown in Fig. 16.

The grinding operation now proceeds, the table 1 traversing back and forth through a small adjustable range, and the pawls 7 3 and 7 9 reciprocating, owing to the 'admission of Huid through the pipes 84 and 85 into the cylinder 86. The pawl 73 undergoes a mere idle movement, because the pawl 79 moves so much further andcauses rotation of the ratchetwheel 68 and an intermittent revolution of the involute cam 62. This gradually moves the lever 59, and shifts the cross slide 54.- on the ways 58, thus moving the workpiece deeper and deeper into engagement with the grinding wheel 5. This action takes place without change until such time as, by the gradual movement of the ratchet wheel 68, the cam-111 engages the adjustable screw 112 and moves the arm 113 so far as to carry the Contact 117 into engagement with the contact terminal 119. This causes energization of the electromagnet 100, which puts out of action the cross feed pawl 79, and allows the pressure on the wheel 'spindle 6 to gradually subside.

A predetermined but adjustable number of reciprocations of the grinding wheel 5 after this point, the movement of the arm 113 is carried suiiiciently further to bring into engagement the contact terminals 116 and 118. This causes energization of the electromagnet 36, lifting the latch 31, and allowing the table 1 to withdraw for a limited distance to the right, being returned by the resetting member 43 to its position of limited reciprocation. Such amplified traverse of the table 1 and grindinu` wheel 5vis made use of todi-ess the rapidly rotating grinding wheel, since a dressing device 145 is at that time disposed in the path of said wheel, by. reason of. the movement of the valve member 153 to the right, resulting in movement of the piston 156 and co uentlv rearward motion of the lever 147, all as previously set fort-h.. It should be particularly observed, that the dressing'operation 

